Multiple position bicycle seat post

ABSTRACT

A bicycle seat position changer is provided which allows the rider to quickly change the effective seat tube angle of the bicycle without requiring the use of tools. The seat position changer allows the rider to move the seat between a forward position and a rearward position, allowing a rider to select a more aerodynamic position or a traditional road position while riding, as required for comfort or by riding conditions. The seat position changer allows the rider to adjust the seat position between the forward and rearward positions while maintaining a consistent difference in seat-to-bottom-bracket length. In one embodiment the consistent difference in seat-to-bottom-bracket length is close to zero and imperceptible to the rider.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage Entry of International ApplicationPCT/US2014/036856, filed on May 5, 2014, which claims benefit ofpriority of U.S. Provisional Patent Application Ser. No. 61/818,999filed on May 3, 2013, the entire disclosures of which are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates in general to bicycle seat posts and inparticular to means for adjusting the position of bicycle saddlesrelative to the seat posts.

BACKGROUND

Bicycles have been around since the early 1800s. The design of thebicycle is continuously being improved, increasing its efficiency invarious aspects. The result is that today we have sleek, lightweight andfast bicycles which are capable of efficiently transferring the energyfrom the cyclist's legs to the wheels of the bicycle.

Cyclists have many different bicycle styles to choose from, each withtheir own advantages and disadvantages. However, there are generally twopositions used for road cycling, a more upright position as seen whenusing road bikes, hybrids and mountain bikes, and a more aerodynamic,forward leaning position as seen on time-trial or triathlon bicycles.Cycling enthusiasts frequently desire the advantages of both ridingpositions. For example, an aerodynamic, forward leaning position isoften desirable at higher speeds, when a rider is seeking to minimizewind resistance. The more upright position is often preferred on roadbicycles when the rider is climbing hills, maneuvering within a group ofriders, or maximizing comfort.

One of the big differences in design on bicycles with these twodifferent styles of riding is the seat (aka “saddle”) position.Specialized bicycles, such as those designed for triathlons or timetrials, have steeper seat tube angles that place the saddle furtherforward relative to the bottom bracket. This allows the rider to assumea more aerodynamic position where arms are extended further forward ontocantilevered aero bars and shoulders are lowered, thus reducing arider's frontal area and creating a more aerodynamic shape. Clip-on aerobar extensions have been developed for road bicycles to allow riders toachieve a similar aerodynamic position, but their use puts the rider inan uncomfortably stretched out position due to the limited forwardtravel adjustment of the typical seat. Another problem can occur whenlowering the torso to assume an aerodynamic position: For a riderbending down and forward into aerobars without adjusting the saddleposition, the rider's hip-angle (the angle between the rider's torso andupper leg at the top of the pedal stroke) can become cramped anduncomfortable.

Road bicycle seat posts typically allow adjustment to the height, tilt,and fore-aft position of the saddle within a limited range. However, ifa road bicycle cyclist desires to have a more aerodynamic position, herequires specialized seat posts to place the saddle in a significantlyfurther forward position. Once installed, the seat post does not allowthe seat to be moved back to a position that would be suitable fornormal upright road riding without reinstalling the traditionallypositioned seat post.

Likewise, typical saddles assemblies require adjusting the tilt or “seatangle” by loosening a bolt, physically manipulating the position of thesaddle to the desired seat angle or tilt, then tightening the bolt tohold the saddle in fixed position. For a rider wanting to change ridingstyles during a ride, changing the seat angle requires getting off thebicycle to perform these adjustments. For a rider wanting to frequentlyalternate between two riding styles, there is no way to rapidly, easily,and reliably switch between two reliably consistent seat angles.

The traditional saddle position on a road bike can be uncomfortable whenusing aero bars and the forward saddle position used with aero bars isnot suitable when conditions call for a more traditional upright roadposition. Switching seat posts is time consuming, may require the use oftools, and typically cannot be done in the middle of a ride. There isthus a need for a means to easily adjust the saddle position during aride that does not require the use of tools or the replacement of a seatpost.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a seat position changer in the rearwardposition with a saddle installed.

FIG. 2 is a side view of a seat position changer in the forward positionwith a saddle installed.

FIG. 3 is an isometric view of a seat position changer in the forwardposition with a saddle installed.

FIG. 4 is an exploded isometric view of a seat position changer.

FIG. 5 is a simplified side view of a four bar linkage attached to aseat post in the rearward (dotted lines) and forward positions (solidlines).

FIG. 6 is a simplified side view of a four bar linkage attached to aseat post in the rearward (dotted lines) and forward positions (solidlines).

FIG. 7 is a detailed side view of two lower linkages juxtaposed to showa change in shaft position by rotating an eccentric shaft.

FIG. 8 is an isometric view of an eccentric shaft.

FIG. 9 is a detailed cross-section of a four bar linkage showing anexample of how a detent mechanism and eccentric elements may beconfigured within a four bar linkage.

FIG. 10 is an isometric view of the seat position changer showing anexample means of adjustably attaching the lower linkage to the seatpost.

FIG. 11 is a side cross-section view of the seat position changershowing an exemplary means of adjustably attaching the lower linkage tothe seat post.

DETAILED DESCRIPTION OF THE INVENTION

Provided herein is a means for altering the position of a saddle on abicycle without the use of tools or replacement of a seat post. As usedherein, the term “bicycle” means a standard sized, adult, diamond framedbicycle, as commonly understood in the art. The bi-stable dual positionchanger as described herein is a four bar linkage with at least twostable resting positions, allowing a cyclist to quickly, easily, andreproducibly alternate between two seat positions, e.g., a traditionalupright rearward position or a more aerodynamic forward position, asconditions or riding requirements change. As used herein, the term “fourbar linkage” means a mechanical linkage mechanism having four links,connected together with four shafts to form a closed loop in which allof the shafts are substantially parallel to one another andsubstantially perpendicular to the links along at least one axis.

The seat position changer as described herein allows a cyclist to useone bicycle under a variety of conditions. For example, if a cyclist isriding on a flat road, in a time trial or triathlon, minimizing windresistance is important and the cyclist may use the more aerodynamicforward riding position. Alternatively, when a cyclist is maneuvering ordrafting within a group of cyclists or riding uphill, the cyclist mayswitch to a more traditional upright road riding position to providemore power or better handling of the bicycle under those conditions. Insome circumstances, adopting an upright position can provide increasedsafety and comfort for the rider.

The seat position changer may be constructed from a variety of differentmaterials. In some embodiments, the components may be constructed fromessentially any material which provides sufficient structural rigidityfor the application. Examples of appropriate materials include, but arenot limited to, metals (e.g. aluminum, steel, stainless steel, titanium,magnesium, etc.), plastics (e.g. nylon, glass-filled nylon, acetal,polypropylene, ABS, etc.), wood, composites (e.g. carbon fiber), resin,rubber and foam. Fabrication of the components can be accomplished usinga wide variety of established manufacturing techniques including, butnot limited to, machining, molding, casting, extruding, forging,laminating, and welding.

In some embodiments, the four bar linkage of the seat position changercomprises an upper linkage, a lower linkage, a front linkage and a rearlinkage. The linkages may be in any useful shape. In some embodiments,they may be a rectangular bar shaped linkage. In additional embodiments,the linkages may include a channel or hole through the ends allowingthem to be connected together by a shaft.

The linkages are connected such that the saddle position can be changedbetween a forward position and rearward position while maintaining aconsistent difference between (a) the seat-to-bottom-bracket length inthe forward position and (b) the seat-to-bottom-bracket length in therearward position. As used herein, the term “consistent difference”means that variability or deviation (if any) in the difference between(a) the seat-to-bottom-bracket length in forward position and (b) theseat-to-bottom-bracket length in the rearward position is imperceptibleor immaterial to the rider across a range of bicycle installations. Inone embodiment, the consistent difference in seat-to-bottom-bracketlength is between about 0.01 cm to about 0.1 cm. In one embodiment, theconsistent difference in seat-to-bottom-bracket-length is about 0.1 to0.5 cm. In one embodiment, the consistent difference inseat-to-bottom-bracket-length is about 0.5 to 1 cm.

In one embodiment, the difference in seat-to-bottom-bracket-lengthbetween the forward position and the rearward position may be chosen bythe rider. In one embodiment the difference inseat-to-bottom-bracket-length between the forward position and therearward position is imperceptible to the rider. In one embodiment, thedifference in seat-to-bottom-bracket-length between the forward positionand the rearward position is between 0 and about 0.01 cm. In oneembodiment, the difference in seat-to-bottom-bracket-length between theforward position and the rearward position is between about 0.01 mm toabout 0.1 cm. In one embodiment, the difference inseat-to-bottom-bracket-length between the forward position and therearward position is between about 0.1 cm to about 1 cm. In oneembodiment, the difference in seat-to-bottom-bracket-length between theforward position and the rearward position is between about 1 cm toabout 5 cm.

In one embodiment, the linkages are connected such that the saddleposition can be changed between a forward and rearward position whilemaintaining a difference in seat-to-bottom-bracket length of about zero,such that the difference is imperceptible to the rider. As used herein,the term “consistent seat-to-bottom-bracket length in both positions”means maintaining a consistent difference in seat-to-bottom-bracketlength of about zero when changing between a forward and rearwardposition.

In one embodiment, the linkages are connected such that the saddleposition can be changed between a forward and rearward position whilemaintaining a consistent seat-to-bottom-bracket length in bothpositions. The seat-to-bottom bracket length remains consistent in bothpositions throughout the range of seat-to-bottom-bracket lengthsgenerally found on standard adult bicycles. By maintaining consistentseat-to-bottom-bracket length in both positions, changes to the rider'sknee angle (the angle between the rider's upper and lower leg when theleg is fully extended) between the forward and rearward seat positionsare imperceptible or immaterial to the rider.

The change in seat-to-bottom bracket length between the two positionsremains consistent throughout the range of seat-to-bottom-bracketlengths generally found on standard adult bicycles. In this embodiment,the seat-to-bottom-bracket length is quickly, consistently, andprecisely changed to the rider's predefined specifications when the seatposition is changed between the forward and rearward positions.

As used herein, the term “seat-to-bottom-bracket length” refers to thedistance between a fixed point on a bicycle seat (e.g., the center ofthe saddle rails) and the bicycle's bottom bracket. The term “bottombracket” is defined as the point where the axis of rotation of thebicycle crankset (made up of the pedals, crank arms, and chain rings)intersects the vertical center-plane of the bicycle. Throughout thisapplication, reference is made to seat-to-bottom-bracket length. Thisterm is used within the context of selecting specific riding positionsfor affecting a cyclist's pedaling motion. For example, preserving acyclist's pedaling motion could include maintaining a consistent kneeangle during the part of the pedal stroke where the cyclist's leg ismost extended. Alternatively, purposefully changing a cyclist's pedalingmotion could include configuring the seat changer to switch betweenperceptibly different seat-to-bottom-bracket-lengths when switchingbetween the forward and rearward positions.

The upper and lower linkages of the four bar linkage of the seatposition changer are independently connected to the front and rearlinkages to form a mechanism that is approximately rectangular whentransferring between positions and has a forward and rearward restingposition, allowing for an easy change between positions and stabilityonce the position is selected.

In one embodiment, the disclosed method of changing seat positionscomprises securing the four bar linkage in a fixed position in which twolinkages chosen from the upper linkage, the lower linkage, the frontlinkage, and the rear linkage rest against each other. For example, inone embodiment, the four bar linkage of the seat position changer couldbe configured such that the front and rear linkages rest against oneanother when positioned in either the forward position or the rearwardposition. In an alternate embodiment, the four bar linkage of the seatposition changer could be configured such that the upper and lowerlinkages rest against one another when positioned in either the forwardposition or the rearward position. Within the context of thisdisclosure, the term “rest against” should be interpreted an includingdirect contact between two rigid bodies or contact that includes anon-rigid intermediary layer, such as a noise-absorbing and/or shockabsorbing elastomeric material.

In some embodiments, the upper and lower or front and rear linkages restagainst one another while having a thin elastomeric material sandwichedin between the two resting surfaces by affixing the elastomeric materialto one or both of the surfaces. The elastomeric material could be anymaterial capable of absorbing and dampening vibrational energytransferred through the bicycle, post, and/or four bar linkage. As usedherein, the term “elastomeric material” means a material, such asnatural or synthetic rubber, that is able to resume its original shapewhen a deforming force is removed. In one embodiment of the disclosedbi-stable dual position seat changer, a thin elastomeric material isaffixed at a point where two linkages contact one another. In someembodiments, placing an elastomeric material between these contactpoints provides benefits by dampening, absorbing, or buffering thevibrational energy created by the act of riding a bicycle.

The four bar linkage formed by the lower linkage, the upper linkage, thefront linkage, and rear linkage is designed to allow the saddle to movealong a curved path between a rearward position and a forward position.The upper linkage and the front linkage are connected by a shaft whichpasses perpendicularly through the linkages. Each linkage can rotateabout or around the axis of rotation to change the position of thesaddle assembly. The front linkage and the lower linkage are connectedby a second shaft passing perpendicularly through the front linkage andthe lower linkage and allowing for a second axis of rotation around thesecond shaft. The lower linkage and the rear linkage are similarlyconnected by a perpendicular shaft forming a third axis of rotationabout the third shaft. The upper linkage and the rear linkage areconnected by a fourth shaft passing perpendicularly through the upperand rear linkages and providing a forth axis of rotation. In someembodiments the shafts may be conventional cylindrical shafts. In otherembodiments, one or more shafts may include eccentric portions which arenot coaxial with a shafts primary axis of rotation. In one embodiment, ashaft may pass through one or more bushings such as, but not limited to,eccentric bushings, solid sleeve bushings, and/or flanged bushings.

The seat may move through a curved path between a forward and rearwardposition by rotating about one or more of the shafts. In one embodiment,moving the seat through a curved path is accomplished by attaching theseat to a four bar linkage which governs the path of movement. In thisembodiment, both the path and the angle (or tilt) of the seat arecontrolled by the geometry of the four bar linkage when moving betweenthe rearward and forward positions.

The upper linkage of the seat position changer may be rigidly connectedto the saddle by any means generally used to attach bicycle seat postsand saddle assemblies. As used herein the term “rigidly connected” meansattached together, forming a solid, stiff junction. In otherembodiments, multiple bolts may be used to securely attach the saddleand saddle clamp to the upper linkage.

In some embodiments of the invention, the lower linkage is integrateddirectly into the top of the seat post tube. In these embodiments, theinvention replaces the entire bicycle seatpost and attaches directly tothe frame of bicycle. In other embodiments, a clamp or joint may be usedto attach the lower linkage to the seat post. In one embodiment of theinvention, the lower linkage does not integrate directly with theseatpost tube, and instead includes a pair of parallel cylindrical railswhich replicate the saddle rails found on the underside of a standardbicycle saddle. In this embodiment, the seat position changer can beattached to a standard seatpost by clamping these rails in the saddleclamp of the standard seatpost. In this embodiment, the seat positionchanger is placed between the seatpost and saddle of a standard bicycle.

The saddle further has at least two resting positions where one linkagecontacts another linkage, creating a stop. In one example, the forwardlinkage contacts the aft linkage. In another example the upper linkagecontacts the lower linkage. In some embodiments, an end stop is providedwhich prevents the saddle from moving too far forward or too far back.In additional embodiments, angular travel stops may be inserted where aportion of the forward and/or aft linkages rest on a part of the upperor lower linkage, limiting the range of motion of the seat. In otherembodiments, the saddle may be maintained in the forward or aft positionthrough the use of a detent. Any appropriate detent known to those ofskill in the art may be used. In some embodiments, the detent maycomprise a detent on one or more of the linkages, a detent rod whichengages the detent, and a spring to apply force to the detent rod. Inother embodiments, the action of the linkage mechanism and the weight ofthe cyclist serve to keep the saddle in the forward or aft position.

In one embodiment of the bi-stable dual position seat changer, at leastone of the forward position and the rearward position is anenergetically favored resting position. As used herein, the term“energetically favored resting position” means a position in which thegravitational and spring forces acting on the device favor thatposition. For example, for a seat changer having a range of motionspanning a curved path of movement, the “energetically favored restingposition” would describe positions favored by the gravitational andspring forces acting on that range of motion. In one example, anenergetically favored resting position would describe the lowerendpoints of a curved path range of motion, where gravitational forceswould favor moving the seat. In some embodiments, the linkages “restagainst each other” in the energetically favored positions, providingadditional rigidity and stability. For a bicycle seat changer,positioning the seat in an “energetically favored resting position”provides an advantage in terms of stability because the forces acting onthe seat reinforce the positioning rather than working against thepositioning. By positioning the seat in an “energetically favoredresting position,” the need for locking mechanisms and positions isoften unnecessary. However, in some embodiments of this disclosure,locking positions are used to reinforce the security of either or bothof the forward position or the rearward position of the bicycle seatchanger. In one embodiment of the bi-stable dual position seat changer,each of the forward position and the rearward position is anenergetically favored resting position.

The seat position changer moves between resting positions through asmall curved path using the four bar linkage until the forward linkageand the aft linkage rest on each other. The length of the curved pathmay be adjusted by altering the distance between the second shaft andthe third shaft and/or adjusting an eccentric bushing and/or eccentricshaft, allowing a cyclist to tailor the amount forward or aft that theseat is allowed to move during a ride to a cyclist's personalpreferences. In some embodiments, spacers may be placed between theforward linkage and/or the aft linkage, limiting the curved path oftravel in one or both directions and thus limiting the range of motionof the saddle.

One example of the seat position changer as described herein is shownwith a saddle attached in a side view in the rearward position inFIG. 1. As used herein, the term “seat” means a surface on which aperson sits. A bicycle seat should be understood as any seat attached toa bicycle, for example by way of attaching a seat to a seat post. Asused in the art, the term bicycle “seat” should be understood as havingthe same meaning as a bicycle “saddle.” As shown in FIG. 1, the rearwardposition places the saddle in a location comparable to a standard roadbicycle saddle position with the centerline of the saddle clamp slightlyoffset behind the axis of the seat post and enables a rider to attain atraditional upright riding position. A lower linkage (1) is integratedwith a seat post (22) such that they are formed as one piece. An upperlinkage (2) is clamped by a saddle clamp lower (10) and a saddle clampupper (11) to the saddle rails (5) such that the saddle (4) can beloosened and removed from the clamp. A front linkage (6) and rearlinkage (7) may rotate along an axis to change the position of the seat(4). In some embodiments the four bar linkage may be removably attachedto the seat post (22), such as with a clamp or other fastening device.The angle between the lower linkage (1) and the seat post (22)determines the path the saddle follows when the seat position changer ismoved from the rearward to forward position or vice versa. In someembodiments the angle of the lower linkage (1) is set such that thesaddle (4) to bottom bracket (not shown) distance is consistentregardless of whether the seat is in the forward or rearward position.

Referring now to FIG. 2, a side view of a seat position changer in theforward position is shown. This forward position places the saddle in aposition often preferred during triathlon training and racing, allowinga cyclist to obtain a more aerodynamic position. As can be seen incomparison to FIG. 1, the angle of the front linkage (6) and rearlinkage (7) have changed. Also, compared to FIG. 1, the saddle (4),saddle clamp lower (10) and saddle clamp upper (11) have moved forwardrelative to the position of the lower linkage (1), which is integratedwith the seat post (22).

An isometric view of the seat position changer in the forward positionis shown in FIG. 3. As shown, a first end of the front linkage (6) isconnected to a first end of the lower linkage (1), which is integratedwith the seat post. A first end of the rear linkage (7) is connected toa second end of the lower linkage (1). A first end of the upper linkage(2) is connected to a second end of the front linkage (6). A second endof the rear linkage (7) is connected to a second end of the upperlinkage (2). The upper linkage (2) is further connected to the saddle(4) by clamping the saddle rails (5) between the lower saddle clamp (10)and the upper saddle clamp (11).

An exploded isometric view of a seat position changer as shown in FIG. 4provides additional detail. The seat post (22) is integrated with thelower linkage (1) of the seat position changer. A first end of the frontlinkage (6) fits around the front end of the lower linkage (1). Thefront linkage (6) fastens around the lower linkage (1) by means of anyfastener generally used to attach such pieces including, but not limitedto, a bolt, a screw, a peg, a linkage shaft, and the like. As shown inFIG. 4, a linkage shaft (14) passes through a shaft bushing sleeve (20)and a thrust washer (21) through a first side of the front linkage (6),out a second side of the front linkage (6), through a first side of thefront end of the lower linkage (1), out a second side of the front endof the lower linkage (1) through a third side of the front linkage (6),out a fourth side of the front linkage and through a flanged bushing (9)to lock in place. In some embodiments the linkage shaft (8) is the sameat all connection points. In other embodiments, different linkage shaftsmay be used at different connection points. For example, the shaft (8)may be the same through both a first end of the front linkage (6) and asecond end of the front linkage (6), or the shafts (8) and (14) may bedifferent as shown. The bushing (9) is an approximately cylindricallining for an opening used to limit the size of the opening, resistabrasion, or serve as a guide. Any type of lining that will serve thispurpose may be used, or no lining at all may be used. A bushing may beof any type generally used, including, but not limited to, an eccentricbushing, a standard bushing, a flanged bushing, a solid sleeve bushing,or a combination thereof. Similarly to the front linkage (6), a shaft(8) passes through a flanged bushing (9) through a first side of therear linkage (7), out a second side of the rear linkage (7), through afirst side of the back end of the lower linkage (1), out a second sideof the back end of the lower linkage (1) through a third side of therear linkage (7), out a fourth side of the rear linkage (7), and througha flanged bushing (9).

Additionally as shown in FIG. 4, a second end of the front linkage (6)is attached to the upper linkage (2) of the seat position changer. Alinkage shaft (8) passes through a flanged shaft bushing (9) and througha hole in a first side of a second end of the front linkage (6). Thelinkage shaft (8) then passes through a first side of the front end ofthe upper linkage (2), out a second side of the upper linkage (2)through a third side of the second end of the front linkage (6), out afourth side of the second end of the front linkage (6), though a flangedbushing (9).

A second end of the rear linkage (7) is attached to the upper linkage(2) of the seat position changer. A linkage shaft (8) passes through aflanged shaft bushing (9) and through a hole in a first side of the rearlinkage (7). The linkage shaft (8) then passes through a first side of asecond end of the upper linkage (2), out a second side of the second endof the upper linkage (2) through a third side of the second end of therear linkage (7), out a fourth side of the second end of the rearlinkage (7), though a flanged bushing (9). In some embodiments, theshafts are secured by being press fit into a lower linkage (1) or upperlinkage (2).

The seat position changer is attached to the saddle rails (not shown) byany means or series of clamps generally used. In one embodiment, theseat position changer is attached to the saddle rails using a clampingsystem comprising saddle clamp bolts (3), a saddle clamp lower piece(10) and a saddle clamp lower piece (11). The saddle clamp bolts (3)pass through the upper linkage (2), around the saddle clamp lower piece(10), through the saddle clamp upper piece (11) and into a saddle clampnut (19), clamping the saddle rails (not shown) between the saddle clamplower piece (10) and the saddle clamp upper piece (11). In someembodiments, the facing sides of the saddle clamp lower piece (10) andthe saddle clamp upper piece (11) contain a groove for attaching to thesaddle rails (not shown).

Different sized cyclists can be accommodated on the seat positionchanger by changing the length of the front (6) and rear (7) linkages,thus increasing or decreasing the distance between the rearward andforward positions. The range of motion in each direction is set by thegeometry of the linkages such that at either end of the curved path,either the front (6) and rear (7) linkages, or the upper (2) and lower(1) linkages are resting on each other. This provides for two stablepositions, allowing the cyclist to sit, stand, and pedal securely ineither the forward or rearward positions. In some embodiments, a sectionof elastomeric material may be attached to the front (6) and rear (7)linkages at the location where the two linkages rest against each otherin the rearward and forward positions. In another embodiment, a sectionof elastomeric material may be attached to the upper (2) and lower (1)linkages at the location where the two linkages rest against each other.The elastomeric material (18) muffles or eliminates noise generated ifthe front and rear linkages temporarily separate and come back intocontact such as when a rider hits a bump or during other instances whereforces push the saddle assembly off of one of its end stops. In otherembodiments, a more significant amount of elastomeric material (18) maybe attached to the front (6) and rear (7) linkages to absorb shock andvibration that is transmitted to the cyclist through the seat post.

In one embodiment, the bi-stable dual position seat changer comprises aseat, rigidly connected to the said upper linkage and forming a seatangle, said seat angle determined by comparing the plane of the seat tothe plane of the ground when the said bi-stable dual position seatchanger is installed in an upright bicycle with its wheels positioned ona flat surface; and wherein the seat angle in the rearward restingposition differs from the seat angle in the forward resting position. Byconfiguring the seat changer with different saddle tilt in the forwardand rearward positions, the rider can easily, rapidly, and reliablychange the seat angle by switching from a forward position to a rearwardposition.

As used herein, the term “seat angle” refers to the angle formed betweenthe plane of the seat to the plane of the ground when a bicycle seat isinstalled in an upright bicycle with its wheels positioned on a flatsurface. Most often bicycles are set up so that the seat angle is fairlyclose to horizontal, meaning that the plane of the bicycle seat isparallel to the plane of the ground when the bicycle seat is installedin an upright bicycle with its wheels positioned on a flat surface.However, many riders prefer slightly adjusting the seat angle by tiltingthe seat up or down. Changing the seat angle is also referred to aschanging the “tilt” of the seat.

FIGS. 5 and 6 demonstrate how different linkage lengths within the fourbar linkage can be altered to achieve different seat angles relative tothe seat post. As shown in FIG. 5, the angles of the upper linkage (2)to the lower linkage (1) are the same in both the rearward (dottedlines) and forward (solid lines) position. In FIG. 5, the linkages areconnected by four linkage shafts (8) (represented here by the balls onthe ends of the linkages). The upper linkage (2) rotates forward tochange the position of the saddle from rearward (dotted lines) toforward (solid lines), but the seat angle does not change. FIG. 6 showsa shorter lower linkage (1) which causes the upper linkage angle tochange relative to the lower linkage (1) when changing positions suchthat seat angle is different in the forward position.

In some embodiments, length of the lower linkage may be altered throughthe use of an eccentric shaft or bushing. For example, the shaft (14)may be eccentric such that the central section of the shaft is notconcentric with the end portions of the shaft as shown in FIG. 8. Theshaft (14) can rotate within the front lower linkage bore allowing theaxis of the end portions of the shaft (14) to move perpendicular to theaxis of the central section thus changing the effective distance betweenthe front and rear linkage pivot points as shown in FIG. 7. This allowsthe saddle to be tilted at a different angle in the forward positionrelative to the rearward position. The adjustment is made on theeccentric shaft (14) seen in FIG. 7. The eccentric shaft (14) shown inFIG. 8 is adjustable. In one embodiment, the bi-stable dual positionseat changer comprises a means for changing the location of the axis ofrotation of at least one shaft. As used herein, the term “means forchanging the location of the axis of rotation of the at least one shaft”refers to any mechanical device capable of moving the location of theaxis of rotation of the shaft. In one embodiment, changing the axis ofrotation of the at least one shaft is accomplished by incorporating aneccentric element into the shaft. For example, an eccentric elementwould include a “shaft having sections offset from the center.” Inanother embodiment, in the lower linkage (1) inserts which have shaftbores at precise locations that position the shaft to achieve differentamounts of forward saddle tilt are used. The inserts are retained in thelower linkage with a clamping bolt or set screw. An alternativeembodiment removes this adjustability all together and replaces theeccentric shaft (14) with standard shafts (8). Another embodiment useseccentric bushings instead of eccentric shafts to change the location ofthe axis of rotation of a shaft (8).

In one embodiment, the disclosed method of changing seat positionscomprises securing the four bar linkage by applying force to at leastone of upper linkage, a lower linkage, a front linkage, and a rearlinkage. As used herein, the term “securing the four bar linkage byapplying force to at least one of upper linkage, a lower linkage, afront linkage, and a rear linkage” means applying force through a massto the surface of one of the linkages to create friction between themass and the linkage. Applying force in this manner results in addedsecurity by requiring the user to overcome a certain degree of staticfriction in order to move the four bar linkage. The degree of securitycan be modified by adjusting the amount of static friction by choosingthe desired amount of force and coefficient of static friction. In oneembodiment, securing the four bar linkage includes applying force via aspring to a rod. In another embodiment, securing the four bar linkageincludes a detent mechanism, such that applying force via a spring to arod causes the rod to engage with a detent profile in one of thelinkages. Once engaged, the rod and detent interaction provide a barrierto moving out of that position, thereby adding stability and security tothe chosen position. In one embodiment, the disclosed method of changingseat positions comprises applying spring force through a detent rod toat least one of upper linkage, a lower linkage, a front linkage, and arear linkage. In one embodiment, the detent rod engages with a detent,securing the four bar linkage into position.

In some embodiments, as shown in FIG. 9, a detent (15) may be used tohold the saddle in place in the forward or rearward positions against anend stop (not shown). Any type of detent mechanism known to those ofskill in the art may be used, for example, a lever, a pin, a springloaded catch, or ratcheting mechanism. In some embodiments, the detentmechanism may be a spring loaded rod as shown in FIG. 9. The spring (17)and rod (16) sit in the rear linkage (7) and apply force to a detentprofile (15) in the lower linkage (1). The spring (17) loaded rod (16)rod is forced into a linkage detent profile (15) when the saddle is ineither the rearward or forward position. The rod (16) applies force tothe lower linkage (1) such that the saddle will remain in place untilenough force is applied in the opposite direction to push the rod (16)out of the detent profile (15), allowing the linkage to rotate to theother position. In some embodiments, the detent profile (15) in thelower linkage (1) is designed such that when the seat changer mechanismis close to either the rearward or forward position the force generatedby the spring (17) and rod (16) will push the seat changer towards anend stop. The force required to move the seat changer is easily appliedwith a single hand allowing the cyclist to change the position of theseat to the forward or rearward position while riding the bicycle andwithout the use of additional tools. Alternatively, the rider can movethe saddle by using the inner thighs to squeeze the saddle and apply aslight upward and forward or backward force, allowing the cyclist tomaintain two hands on the handlebar. In some embodiments, the detent maybe composed of magnets between two moving linkages. When the four barlinkage approaches the rearward or forward position, the magnets comeinto alignment and keep the saddle in the desired position.

In one embodiment, the detent rod and spring are housed in the rearlinkage, applying force to the lower linkage, and engaging a detentprofile on the lower linkage. In another embodiment, the detent rod andspring are housed in the upper linkage, applying force to the frontlinkage, and engaging a detent profile on the front linkage. Otherarrangements of the detent mechanism are possible, provided that theyserve to stabilize the desired seat positions, for example positionsproviding the rider with a consistent seat-to-bottom-bracket-length.

In additional embodiments, a locking mechanism for either the forward orrearward position or both requires the cyclist to actuate a button orlever or use a tool to release the mechanism from its current position.In some embodiments the actuator could be located directly on themechanism.

In one embodiment, as shown in FIGS. 10 and 11, the lower linkage (1) isrigidly connected to the seat post (22) using a joint (25) that allowsfor angular adjustment between the lower linkage (1) and the seat post(22). Changing the angle between the lower linkage (1) and the seat post(22) alters the trajectory of the curved path that the seat (4) travelson between the forward and rearward positions. Changing the trajectoryof the curved path allows the user to increase or decrease theseat-to-bottom-bracket length in the forward position relative to theseat-to-bottom-bracket length in the rearward position. This embodimentuses a pinned connection (23) between the lower linkage (1) and seatpost (22), as well as a pair of bolts (24) to adjust the angle of thelower linkage (1) relative to the seat post (22) and to fix its positionrelative to the seat post (22).

In an alternative embodiment, the lower linkage is shaped so that itinterfaces directly with the saddle clamping mechanism of any standardseat post. In this embodiment, the lower linkage may include geometrythat replicates the rails of a standard bicycle saddle, allowing it tobe clamped directly into any standard seat post in the same manner thata saddle would be clamped into a standard seat post. Alternatively, thelower linkage may include geometry that replicates portions of thesaddle clamp geometry found on any standard seat post, allowing thelower linkage to replace certain saddle clamp pieces of the seat postassembly. In these embodiments, changes to the tilt adjustment mechanismon the standard seat post result in an effective change to the anglebetween the lower linkage and the seat post, thereby altering thetrajectory of the curved path of the seat.

While several embodiments of a seat position changer have been shown anddescribed, it will be apparent to those skilled in the art that variousmodifications may be made without departing from the spirit of the seatposition changer described herein.

We claim:
 1. A bi-stable dual position seat changer, comprising: a fourbar linkage having a forward position and a rearward position, each ofsaid forward position and said rearward position providing a consistentseat-to-bottom-bracket-length wherein said four bar linkage comprises anupper linkage, a lower linkage, a front linkage, a rear linkage; a firstshaft, connecting the upper linkage to the front linkage by passingperpendicularly through each of the upper linkage and front linkage andforming a first axis of rotation about the first shaft; a second shaft,connecting the front linkage to the lower linkage by passingperpendicularly through each of the front linkage and lower linkage andforming a second axis of rotation about the second shaft; a third shaft,connecting the lower linkage to the rear linkage by passingperpendicularly through each of the lower linkage and rear linkage andforming a third axis of rotation about the third shaft; a fourth shaft,connecting the rear linkage to the upper linkage by passingperpendicularly through each of the rear linkage and upper linkage andforming a fourth axis of rotation about the fourth shaft; and a detentmechanism configured for alternatively securing the four bar linkage inthe forward position and the rearward position.
 2. The bi-stable dualposition seat changer of claim 1, wherein at least one of the forwardposition and the rearward position is an energetically favored restingposition.
 3. The bi-stable dual position seat changer of claim 1,wherein each of the forward position and the rearward position is anenergetically favored resting position.
 4. The bi-stable dual positionseat changer of claim 1, wherein the detent mechanism comprises: adetent on the four bar linkage; and a spring-loaded detent rodpositioned to engage the detent.
 5. The bi-stable dual position seatchanger of claim 1, wherein two linkages chosen from the upper linkage,the lower linkage, the front linkage, and the rear linkage contact oneanother in a position chosen from the forward position and the rearwardposition.
 6. The bi-stable dual position seat changer of claim 5,comprising an elastomeric material affixed to at least one of the frontlinkage or the rear linkage.
 7. The bi-stable dual position seat changerof claim 1, wherein the bi-stable dual position seat changer comprises ameans for changing the location of the axis of rotation of at least oneshaft.
 8. The bi-stable dual position seat changer of claim 7, whereinthe means for changing the location of the axis of rotation of the atleast one shaft comprises an eccentric element.
 9. The bi-stable dualposition seat changer of claim 8, wherein the eccentric elementcomprises a shaft having a center and sections offset from the center.10. The bi-stable dual position seat changer of claim 1, comprising aseat, rigidly connected to the upper linkage and forming a seat angle,wherein the seat angle in a first resting position differs from the seatangle in a second resting position.